getting to grips with aircraft performance 如何掌握飞机性能 2(32)

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Supplemental Operations

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Operations for which the departure time, departure location, and arrival location are specifically negotiated with the customer or the customer's representative.

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 All-cargo operations.

2.2. Fuel Policy
The required fuel quantity for a safe trip along the planned route is calculated for each flight. Each operator has its own fuel policy. This policy is based on the loading of minimum regulatory fuel requirements (FAR 121).
2.2.1. Domestic Operations

“FAR 121.639 No person may dispatch or take off an airplane unless it has enough fuel--
(a)
To fly to the airport to which it is dispatched

(b)
Thereafter, to fly to and land at the most distant alternate airport (where required) for the airport to which dispatched; and

(c)
Thereafter, to fly for 45 minutes at normal cruising fuel consumption.”

The minimum fuel quantity (Q) calculated for domestic operation is defined as:
Q = taxifuel + TF + AF + FR
Where:
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 TF = Trip fuel

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 AF = Alternate fuel

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 FR = Final reserve fuel

Figure I7 illustrates the different fuel quantities and associated flight phases during a typical trip.
Final reserve

DEPARTURE DESTINATION ALTERNATE

2.2.1.1. Taxi Fuel
In order to determine this amount, local conditions at departure and APU consumption should be taken into account.
Taxi fuel is usually a fixed quantity for an average taxi duration.
For the A320 for example, it is equal to 140 kg (300 lb). This corresponds to a 12-minute average taxi fuel. Based on statistics or evaluation, the taxi duration and taxi fuel may need to be adjusted.
2.2.1.2. Trip Fuel
The required fuel quantity from brake release at the departure airport to the landing touchdown at the destination airport. This quantity takes into account the necessary fuel for:
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 Takeoff

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Climb to cruise level

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Flight from the end of climb to the beginning of descent

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Flight from the beginning of descent to the beginning of approach

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 Approach

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Landing at the destination airport

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 Anticipated traffic delays.

Daily weather conditions must also be taken into account.
2.2.1.3. Alternate Fuel
Alternate fuel is the amount necessary to fly to the most distant alternate airport, and takes into account:
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Missed approach at the destination airport,

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Climb from the missed approach altitude to cruise level,

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Flight from the end of climb to the beginning of descent,

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Flight from the beginning of descent to the beginning of approach,
　
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